Process of purifying hydrocarbon oils



L. UNK ET AL,

Filed Deo. 9, 1925 r @wwe/nim Lou/ s L INK NA UPCE B. .HM/.5.

wm@ 25, l929 PROCESS oF PURIFYING HYDROCARBON 011.5

Patented June 25, 1929.

UNITED STATES N 1,718,714 PATENT OFFICE.

LOUIS LINK AND MAURICE B. AMIS, OF BATON ROUGE, LOUISIANA, ASSIGNORSTO STANDARD OIL DEVELOPMENT COMPANY, .A CORPORATION OF DELAWARE.

PROCESS OF PURIFYING- HYDROCARBON,` OILS.

Application vfiled December 9, 1925. Serial No. 74,314.

This invention relates to improvements in the purification of hydrocarbon oils, and more particularly to the removal of sulfur or sulfur-containing compounds from natural or first-run naphtha.

The process of the present invention in a preferred form comprises the treatment of corrosive naphtha with caustic alkali that has taken up certain constituents of cracked hydrocarbon distillates. This material I shall refer to as spent caustic. The principal source of supply at this time is the absorption plants utilized for the treatment of gases from the stills in which pressure distillate is being rerun. In these plants the gases'are passed in I'contact with an absorption oil. The gasoline constituents carried by the gas are absorbed by the oil. The gasoline is removed by steam distillation and is purified by treatment with caustic alkali. The contaminated alkali or spent caustic resulting from this process is the preferred treating agent employed according to our invention.

Spent caustic of similar characteristics may be obtained from other sources. For example, the gases from pressure stills may be passed into contact with the caustic. Gases given off from crude stills during the cracking period ordinarily contain a substantial amount of the desired constituents which may hefiixed by alkali. It may be said in general that gases from cracking stills or coils yield such constituents. and that alkali extracts of many sour distillates produced by pressure cracking processes, or analogous materials,`

yield spent caustic suitable for our purposes.

We have found that spent caustic operates very eiectively in the elimination of difficultly removable sulfur, sulfur-containing compounds, or other corrosive ingredients. Naphtha from certain crudes will not pass the standard corrosion tests, even after washing with alkali or treatment with doctor solution (sodium plumbite). Acid treatment and rer running (distillation with steam) are required in such cases. By the use of spent caustic we obtainan important technical advantage in avoiding the delay and losses incident to these operations.

It is probable that the effectiveness of the spent caustic is due to its content of sulfur compounds, the nature of which is at present obscure. In any event, the spent caustic has the property of freeing naphtha from the det- 5 rimental corrosive constituents, which we the finished stock, giving it an objectionable odor. The alkali extract of pressure still naphtha 0r the like is more eilicient than the na htha itself and imparts no odor to the finlshed oil.

The naphtha and spent alkali should be brought into very thorough admixture if best results are to be secured. We have found that an elongated mixer of the type described be'- low is well suited for this purpose. As a A eneral rule, the lower the specific gravity o the distillate to be treated, the more thoroughly the alkali solution and the distillate must be mixed and the longer the contact between them must be maintained.

A particularly advantageous apparatus for' use in carrying out our process is illustrated in the accompanying drawing, 1n which Fig. 1 is a diagramof a preferred arrangev ment of apparatus for carrying out one form of the process;

Fig. 2 is a vertical section through a portion of the elongated mixing tube; and

Fig. 3 is a transverse section on -line III-III of Fig. 2.

Referring to the drawing, reference numerals 1 and 2 denote respectively a tank for receiving oil to be purified and a receptacle for the treating agent. Tank 1 is connected through line Swith a mixer 4, comprising an elongated chamber or passageway. The receptacle 2 connects with the mixer 4 through line 5. Pumps 6 and 7 may be installed in the lines 3` and 5. A discharge line 8 leads from the mixer to a settling drum 9. A line 10 connects this drum with a continuous treating plant or other suitable means for a final treatment of the naphtha, when such final treatment is required. A draw-olf line 11 is connected near the bottom of the drum and may lead back to the receptacle 2, if` it is desired to recirculate the treating agent.l

Referringfmore particularly to Figs. 2 and 3, the mixer 4 is subdivided internally. by partitions 12 fitted with a short, centrally mounted pipe or nipple 13, provided with perforations 13a. The course of the liquid to b e purified and the treating agent through the mixer follows more or less the iiow lines shown in Fig. 2. Very thorough admixture is obtained by the successive commingling of the liquids as they pass through the several perforated pipes 13. We have found it desirable in some cases to use a mixer of relatively great length', for instance from about ft. to about 500 ft. or more. The diameter of the mixer may be small, say about 12' inches, but larger or smaller mixers may be used.. Suitable valves and other connections may'beiarranged so as to enable any-part of .the mixer to be used alone.

From the drum 9 the purified naphtha and the spent caustic solution are drawn off through lines 10 and 11, previously referred to. The spent alkali solution may usually 'be circulated through the system a number number of refinery operations other than that particularly described above. For example, a better grade of kerosene may be obtained by passing the kerosene together with a caustic solution through. the mixer. This insures substantially complete neutralization and the removai of all traces of acid and sludge..

Various changes and alternative arrangements may be made inthe preferred embodiments of the invention described above, within the scope of the appended claims, in which it is our intention to claim all novelty inherent in the invention as broadly as the prior art permits.

We claim:

l. Process of purifying an uncracked light hydrocarbon distillate containing diiicultly removable corrosive sulfur, comprising bringing the distillate into intimate contact with spent alkali from the treatment of a light fraction obtained by cracking petroleum hydrocarbons.

v 2. Process of treating an uncracked naphtha containing diiicultly removable corrosive sulfur, comprising' bringing the naphtha into intimate Contact with spent caustic prepared by the alkali treatment of naphtha. obtained from gas produced in the distillation of oils under pressure.

LOUIS LINK. MAURICE B. AMlS. 

